How to trim multiple clips to same duration?

Helllo, I have a pretty basic question...
I have tons of b-rolls in tv show I am editing... Their camera man likes to take long shots (10 seconds and more) which I always have to trim down to about 3 sec or less to keep the dynamic in the show...

Is it possible (in adobe premiere pro CS 5.5.) to easily trim all selected clips to lets say 3 seconds... it is frustrating to do it manualy when you have lets say 50 b rolls, with combined duration of 1000 seconds... It expands my timeline and it is so boring to trim them manually... The idea would be to trim to middle 3 seconds and then use slip tool to get the right part of shot with some fine tuning afterwards of course...

I think I found something somewhere about doing it from source monitor, but I can`t find that tutorial anymore...

After a bump here I found a solution in case someone is interested.
It can be done in two ways... first which I now use is to set the in and out points for each clip individually from source monitor and then drag them to timeline all together...
In this way they are already trimmed by in and out point. Setting in and out points via source monitor is also good for reviewing material to use as B rolls later...
Second way is by placing markers on timeline and then using automate to sequence option... clips are automatically trimmed to match the markers...